#include "myjson.h"
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <limits>

namespace myjson {
static const int max_depth = 200;

using std::make_shared;
using std::map;
using std::move;
using std::string;
using std::vector;

struct NullStruct {
  // 运算符重载后，右操作数是 NullStruct
  // 才能够被调用，因此比较结果就已经确定下来了
  bool operator==(NullStruct) const { return true; }
  bool operator<(NullStruct) const { return false; }
};

// 序列化

static void dump(NullStruct, string &out) { out += "null"; }

static void dump(double value, string &out) {
  if (std::isfinite(value)) {
    char buf[32];
    snprintf(buf, sizeof buf, "%.17g", value);
    out += buf;
  } else {
    out += "null";
  }
}

static void dump(int value, string &out) {
  char buf[32];
  snprintf(buf, sizeof buf, "%d", value);
  out += buf;
}

static void dump(bool value, string &out) { out += value ? "true" : "false"; }

static void dump(const string &value, string &out) {
  out += '"';
  for (size_t i = 0; i < value.length(); i++) {
    const char ch = value[i];
    if (ch == '\\') {
      out += "\\\\";
    } else if (ch == '"') {
      out += "\\\"";
    } else if (ch == '\b') {
      out += "\\b";
    } else if (ch == '\f') {
      out += "\\f";
    } else if (ch == '\n') {
      out += "\\n";
    } else if (ch == '\r') {
      out += "\\r";
    } else if (ch == '\t') {
      out += "\\t";
    } else if (static_cast<uint8_t>(ch) <= 0x1f) {
      char buf[8];
      snprintf(buf, sizeof(buf), "\\u%04x", ch);
      out += buf;
    } else if (static_cast<uint8_t>(ch) == 0xe2 &&
               static_cast<uint8_t>(value[i + 1]) == 0x80 &&
               static_cast<uint8_t>(value[i + 2]) == 0xa8) {
      out += "\\u2028";
      i += 2;
    } else if (static_cast<uint8_t>(ch) == 0xe2 &&
               static_cast<uint8_t>(value[i + 1]) == 0x80 &&
               static_cast<uint8_t>(value[i + 2]) == 0xa9) {
      out += "\\u2029";
      i += 2;
    } else {
      out += ch;
    }
  }
  out += '"';
}

static void dump(const Json::array &values, string &out) {
  bool first = true;
  out += "[";
  for (const auto &value : values) {
    if (!first) {
      out += ", ";
    }
    value.dump(out);
    first = false;
  }
  out += "]";
}

static void dump(const Json::object &values, string &out) {
  bool first = true;
  out += "{";
  for (const auto &kv : values) {
    if (!first) {
      out += ", ";
    }
    dump(kv.first, out);
    out += ": ";
    kv.second.dump(out);
    first = false;
  }
  out += "}";
}

void Json::dump(string &out) const { m_ptr->dump(out); }

template <Json::Type tag, typename T> class Value : public JsonValue {
protected:
  // 构造函数
  explicit Value(const T &value) : m_value(value){};
  explicit Value(T &&value) : m_value(move(value)){};

  // 获得类型标签
  Json::Type type() const override { return tag; }

  // 比较
  bool equals(const JsonValue *other) const override {
    return m_value == static_cast<const Value<tag, T> *>(other)->m_value;
  }
  bool less(const JsonValue *other) const override {
    return m_value < static_cast<const Value<tag, T> *>(other)->m_value;
  }

  const T m_value;
  void dump(string &out) const override { myjson::dump(m_value, out); }
}; // class Value

class JsonDouble final : public Value<Json::NUMBER, double> {
  double number_value() const override { return m_value; }
  int int_value() const override { return static_cast<int>(m_value); }
  bool equals(const JsonValue *other) const override {
    return m_value == other->number_value();
  }
  bool less(const JsonValue *other) const override {
    return m_value < other->number_value();
  }

public:
  explicit JsonDouble(double value) : Value(value){};
}; // class JsonDouble

class JsonInt final : public Value<Json::NUMBER, int> {
  double number_value() const override { return m_value; }
  int int_value() const override { return m_value; }
  bool equals(const JsonValue *other) const override {
    return m_value == other->number_value();
  }
  bool less(const JsonValue *other) const override {
    return m_value < other->number_value();
  }

public:
  explicit JsonInt(int value) : Value(value) {}
};

class JsonBoolean final : public Value<Json::BOOL, bool> {
  bool bool_value() const override { return m_value; }

public:
  explicit JsonBoolean(bool value) : Value(value){};
}; // class JsonBoolean

class JsonString final : public Value<Json::STRING, string> {
  const string &string_value() const override { return m_value; }

public:
  explicit JsonString(const string &value) : Value(value) {}
  explicit JsonString(string &&value) : Value(value) {}
}; // class JsonString

class JsonArray final : public Value<Json::ARRAY, Json::array> {
  const Json::array &array_items() const override { return m_value; }
  const Json &operator[](size_t i) const override;

public:
  explicit JsonArray(const Json::array &value) : Value(value){};
  explicit JsonArray(Json::array &&value) : Value(move(value)){};
}; // class JsonArray

class JsonObject final : public Value<Json::OBJECT, Json::object> {
  const Json::object &object_items() const override { return m_value; };
  const Json &operator[](const string &key) const override;

public:
  explicit JsonObject(const Json::object &value) : Value(value) {}
  explicit JsonObject(Json::object &&value) : Value(move(value)) {}
}; // class JsonObject

class JsonNull final : public Value<Json::NUL, NullStruct> {
public:
  JsonNull() : Value({}) {}

}; // class JsonNull

// 静态全局变量
struct Statics {
  const std::shared_ptr<JsonValue> null = make_shared<JsonNull>();
  const std::shared_ptr<JsonValue> t = make_shared<JsonBoolean>(true);
  const std::shared_ptr<JsonValue> f = make_shared<JsonBoolean>(false);
  const string empty_string;
  const vector<Json> empty_vector;
  const map<string, Json> empty_map;
  Statics() {}
}; // struct Statics

static const Statics &statics() {
  static const Statics s{};
  return s;
}

static const Json &static_null() {
  // 这个与上面那个是分开的，不在 Statics 中，因为 Json() 使用
  // statics().null
  static const Json json_null;
  return json_null;
}

// 构造函数
Json::Json() noexcept : m_ptr(statics().null) {}
Json::Json(std::nullptr_t) noexcept : m_ptr(statics().null) {}
Json::Json(double value) : m_ptr(make_shared<JsonDouble>(value)) {}
Json::Json(int value) : m_ptr(make_shared<JsonInt>(value)) {}
Json::Json(bool value) : m_ptr(value ? statics().t : statics().f) {}
Json::Json(const string &value) : m_ptr(make_shared<JsonString>(value)) {}
Json::Json(string &&value) : m_ptr(make_shared<JsonString>(move(value))) {}
Json::Json(const char *value) : m_ptr(make_shared<JsonString>(value)) {}
Json::Json(const Json::array &value) : m_ptr(make_shared<JsonArray>(value)) {}
Json::Json(Json::array &&value) : m_ptr(make_shared<JsonArray>(move(value))) {}
Json::Json(const Json::object &values)
    : m_ptr(make_shared<JsonObject>(values)) {}
Json::Json(Json::object &&values)
    : m_ptr(make_shared<JsonObject>(move(values))) {}

// 访问函数
Json::Type Json::type() const { return m_ptr->type(); }
double Json::number_value() const { return m_ptr->number_value(); }
int Json::int_value() const { return m_ptr->int_value(); }
bool Json::bool_value() const { return m_ptr->bool_value(); }
const string &Json::string_value() const { return m_ptr->string_value(); }
const vector<Json> &Json::array_items() const { return m_ptr->array_items(); }
const map<string, Json> &Json::object_items() const {
  return m_ptr->object_items();
}
const Json &Json::operator[](size_t i) const { return (*m_ptr)[i]; }
const Json &Json::operator[](const string &key) const { return (*m_ptr)[key]; }

double JsonValue::number_value() const { return 0; }
int JsonValue::int_value() const { return 0; }
bool JsonValue::bool_value() const { return false; }
const string &JsonValue::string_value() const { return statics().empty_string; }
const vector<Json> &JsonValue::array_items() const {
  return statics().empty_vector;
}
const map<string, Json> &JsonValue::object_items() const {
  return statics().empty_map;
}
const Json &JsonValue::operator[](size_t) const { return static_null(); }
const Json &JsonValue::operator[](const string &) const {
  return static_null();
}

const Json &JsonObject::operator[](const string &key) const {
  auto iter = m_value.find(key);
  return (iter == m_value.end()) ? static_null() : iter->second;
}
const Json &JsonArray::operator[](size_t i) const {
  if (i >= m_value.size()) {
    return static_null();
  } else {
    return m_value[i];
  }
}

// 比较
bool Json::operator==(const Json &other) const {
  if (m_ptr == other.m_ptr) {
    return true;
  }
  if (m_ptr->type() != other.m_ptr->type()) {
    return false;
  }
  return m_ptr->equals(other.m_ptr.get());
}
bool Json::operator<(const Json &other) const {
  if (m_ptr == other.m_ptr)
    return false;
  if (m_ptr->type() != other.m_ptr->type())
    return m_ptr->type() < other.m_ptr->type();

  return m_ptr->less(other.m_ptr.get());
}

// 解析
// 把字符 c 转义，使其适合输出到错误信息中
static inline string esc(char c) {
  char buf[12];
  if (static_cast<uint8_t>(c) >= 0x20 && static_cast<uint8_t>(c) <= 0x7f) {
    snprintf(buf, sizeof buf, "'%c' (%d)", c, c);
  } else {
    snprintf(buf, sizeof buf, "(%d)", c);
  }
  return string(buf);
}

static inline bool in_range(long x, long lower, long upper) {
  return (x >= lower && x <= upper);
}

namespace {
// 跟踪解析状态的对象
struct JsonParser {
  // 状态
  const string &str;
  size_t i;
  string &err;
  bool failed;
  const JsonParse strategy;
  // 解析失败
  Json fail(string &&msg) { return fail(move(msg), Json()); }
  template <typename T> T fail(string &&msg, const T err_ret) {
    if (!failed) {
      err = move(msg);
    }
    failed = true;
    return err_ret;
  }

  // 过滤空白
  void consume_whitespace() {
    while (str[i] == ' ' || str[i] == 'r' || str[i] == '\n' || str[i] == '\t') {
      i++;
    }
  }

  // 过滤注释
  bool consume_comment() {
    bool comment_found = false;
    if (str[i] == '/') {
      i++;
      if (i == str.size()) {
        return fail("unexpected end of input after start of comment", false);
      }
      if (str[i] == '/') { // 单行注释
        i++;
        while (i < str.size() && str[i] != '\n') {
          i++;
        }
        comment_found = true;
      } else if (str[i] == '*') { // 多行注释
        i++;
        if (i > str.size() - 2) {
          return fail("unexpected end of input inside multi-line comment",
                      false);
        }
        while (!(str[i] == '*' && str[i + 1] == '/')) {
          i++;
          if (i > str.size() - 2)
            return fail("unexpected end of input inside multi-line comment",
                        false);
        }
        i += 2;
        comment_found = true;
      } else {
        return fail("malformed comment", false);
      }
    }
    return comment_found;
  }

  // 过滤垃圾
  void consume_garbage() {
    consume_whitespace();
    if (strategy == JsonParse::COMMENTS) {
      bool comment_found = false;
      do {
        comment_found = consume_comment();
        if (failed)
          return;
        consume_whitespace();
      } while (comment_found);
    }
  }
  // 返回下一个非空白字符，如果已经到达了输入的结尾，则返回零并设置错误标志
  char get_next_token() {
    consume_garbage();
    if (failed)
      return static_cast<char>(0);
    if (i == str.size()) {
      return fail("unexpected end of input", static_cast<char>(0));
    }
    return str[i++];
  }
  // 把 pt 编码成 UTF-8，并把它加入到 out
  void encode_utf8(long pt, string &out) {
    if (pt < 0)
      return;

    if (pt < 0x80) {
      out += static_cast<char>(pt);
    } else if (pt < 0x800) {
      out += static_cast<char>((pt >> 6) | 0xC0);
      out += static_cast<char>((pt & 0x3F) | 0x80);
    } else if (pt < 0x10000) {
      out += static_cast<char>((pt >> 12) | 0xE0);
      out += static_cast<char>(((pt >> 6) & 0x3F) | 0x80);
      out += static_cast<char>((pt & 0x3F) | 0x80);
    } else {
      out += static_cast<char>((pt >> 18) | 0xF0);
      out += static_cast<char>(((pt >> 12) & 0x3F) | 0x80);
      out += static_cast<char>(((pt >> 6) & 0x3F) | 0x80);
      out += static_cast<char>((pt & 0x3F) | 0x80);
    }
  }
  // 解析字符串
  string parse_string() {
    string out;
    long last_escaped_codepoint = -1;
    while (true) {
      if (i == str.size()) {
        return fail("unexpected end of input in string", "");
      }
      char ch = str[i++];
      if (ch == '"') {
        encode_utf8(last_escaped_codepoint, out);
        return out;
      }
      if (in_range(ch, 0, 0x1f))
        return fail("unescaped " + esc(ch) + " in string", "");

      // 处理非转义字符
      if (ch != '\\') {
        encode_utf8(last_escaped_codepoint, out);
        last_escaped_codepoint = -1;
        out += ch;
        continue;
      }

      // 处理转义字符
      if (i == str.size()) {
        return fail("unexpected end of input in string", "");
      }

      ch = str[i++];

      if (ch == 'u') {
        // 提取 4 字节的转义序列
        string esc = str.substr(i, 4);
        if (esc.length() < 4) {
          return fail("bad \\u escape: " + esc, "");
        }
        for (size_t j = 0; j < 4; j++) {
          if (!in_range(esc[j], 'a', 'f') && !in_range(esc[j], 'A', 'F') &&
              !in_range(esc[j], '0', '9')) {
            return fail("bad \\u escape: " + esc, "");
          }
        }
        long codepoint = strtol(esc.data(), nullptr, 16);

        // 处理代理对
        if (in_range(last_escaped_codepoint, 0xD800, 0xDBFF) &&
            in_range(codepoint, 0xDC00, 0xDFFF)) {

          encode_utf8((((last_escaped_codepoint - 0xD800) << 10) |
                       (codepoint - 0xDC00)) +
                          0x10000,
                      out);
          last_escaped_codepoint = -1;
        } else {
          encode_utf8(last_escaped_codepoint, out);
          last_escaped_codepoint = codepoint;
        }
        i += 4;
        continue;
      }

      encode_utf8(last_escaped_codepoint, out);
      last_escaped_codepoint = -1;

      if (ch == 'b') {
        out += '\b';
      } else if (ch == 'f') {
        out += '\f';
      } else if (ch == 'n') {
        out += '\n';
      } else if (ch == 'r') {
        out += '\r';
      } else if (ch == 't') {
        out += '\t';
      } else if (ch == '"' || ch == '\\' || ch == '/') {
        out += ch;
      } else {
        return fail("invalid escape character " + esc(ch), "");
      }
    }
  }
  // 解析数字
  Json parse_number() {
    size_t start_pos = i;
    if (str[i] == '-') {
      i++;
    }
    // 整数部分
    if (str[i] == '0') {
      i++;
      if (in_range(str[i], '0', '9')) {
        return fail("leading 0s not permitted in numbers");
      }
    } else if (in_range(str[i], '1', '9')) {
      i++;
      while (in_range(str[i], '0', '9'))
        i++;
    } else {
      return fail("invalid " + esc(str[i]) + " in number");
    }
    // 如果没有小数部分就直接返回
    if (str[i] != '.' && str[i] != 'e' && str[i] != 'E' &&
        (i - start_pos) <=
            static_cast<size_t>(std::numeric_limits<int>::digits10))
      return std::atoi(str.c_str() + start_pos);

    // 小数部分
    if (str[i] == '.') {
      i++;
      if (!in_range(str[i], '0', '9'))
        return fail("at least one digit required in fractional part");
      while (in_range(str[i], '0', '9'))
        i++;
    }
    // 指数部分
    if (str[i] == 'e' || str[i] == 'E') {
      i++;
      if (str[i] == '+' || str[i] == '-')
        i++;
      if (!in_range(str[i], '0', '9'))
        return fail("at least one digit required in exponent");
      while (in_range(str[i], '0', '9'))
        i++;
    }
    return std::strtod(str.c_str() + start_pos, nullptr);
  }
  // 期望的 expected 以刚刚读入的字符为开头，
  // 然后进行匹配，如果匹配成功则继续推进，
  // 否则就标记错误
  Json expect(const string &expected, Json res) {
    assert(i != 0);
    // 切换到刚刚读入的那个字符
    i--;
    if (str.compare(i, expected.length(), expected) == 0) {
      i += expected.length();
      return res;
    } else {
      return fail("parse error: expected " + expected + ", got " +
                  str.substr(i, expected.length()));
    }
  }
  // 解析 Json 对象
  Json parse_json(int depth) {
    if (depth > max_depth)
      return fail("exceeded maximum nesting depth");
    char ch = get_next_token();
    if (failed)
      return Json();
    if (ch == '-' || (ch >= '0' && ch <= '9')) {
      i--;
      return parse_number();
    }
    if (ch == 't')
      return expect("true", true);
    if (ch == 'f')
      return expect("false", false);
    if (ch == 'n')
      return expect("null", Json());
    if (ch == '"')
      return parse_string();
    if (ch == '{') {
      map<string, Json> data;
      ch = get_next_token();
      if (ch == '}')
        return data;
      while (1) {
        if (ch != '"')
          return fail("expected '\"' in object, got " + esc(ch));
        string key = parse_string();
        if (failed)
          return Json();

        ch = get_next_token();
        if (ch != ':')
          return fail("expected ':' in object, got " + esc(ch));
        data[std::move(key)] = parse_json(depth + 1);
        if (failed)
          return Json();
        ch = get_next_token();
        if (ch == '}')
          break;
        if (ch != ',')
          return fail("expected ',' in object, got " + esc(ch));
        ch = get_next_token();
      }
      return data;
    }
    if (ch == '[') {
      vector<Json> data;
      ch = get_next_token();
      if (ch == ']')
        return data;
      while (1) {
        i--;
        data.push_back(parse_json(depth + 1));
        if (failed)
          return Json();
        ch = get_next_token();
        if (ch == ']')
          break;
        if (ch != ',')
          return fail("expected ',' in list, got " + esc(ch));
        ch = get_next_token();
        (void)ch;
      }
      return data;
    }
    return fail("expected value, got " + esc(ch));
  }
}; // struct JsonParser
} // namespace

Json Json::parse(const string &in, string &err, JsonParse strategy) {
  JsonParser parser{in, 0, err, false, strategy};
  Json result = parser.parse_json(0);

  // 过滤尾部的垃圾
  parser.consume_garbage();
  if (parser.failed)
    return Json();
  if (parser.i != in.size())
    return parser.fail("unexpected trailing " + esc(in[parser.i]));
  return result;
}

// 解析过个 json 对象
vector<Json> Json::parse_multi(const string &in,
                               std::string::size_type &parser_stop_pos,
                               string &err,
                               JsonParse strategy) {
    JsonParser parser { in, 0, err, false, strategy };
    parser_stop_pos = 0;
    vector<Json> json_vec;
    while (parser.i != in.size() && !parser.failed) {
        json_vec.push_back(parser.parse_json(0));
        if (parser.failed)
            break;

        // Check for another object
        parser.consume_garbage();
        if (parser.failed)
            break;
        parser_stop_pos = parser.i;
    }
    return json_vec;
}

bool Json::has_shape(const shape & types, string & err) const {
    if (!is_object()) {
        err = "expected JSON object, got " + dump();
        return false;
    }

    const auto& obj_items = object_items();
    for (auto & item : types) {
        const auto it = obj_items.find(item.first);
        if (it == obj_items.cend() || it->second.type() != item.second) {
            err = "bad type for " + item.first + " in " + dump();
            return false;
        }
    }
    return true;
}

} // namespace myjson